KR-20260065551-A - NEGATIVE ELECTRODE AND LITHIUM SECONDARY BATTERY INCLUDING THE SAME

KR20260065551AKR 20260065551 AKR20260065551 AKR 20260065551AKR-20260065551-A

Abstract

The present invention relates to a cathode comprising: a cathode current collector; a first cathode active material layer located on the cathode current collector; and a second cathode active material layer located on the first cathode active material layer; wherein the volume of pores included in the first cathode active material layer is 20% to 49% of the total volume of pores included in the first cathode active material layer and the second cathode active material layer; wherein the first cathode active material layer includes a first cathode active material comprising natural graphite and a first silicon-based cathode active material, and the second cathode active material layer includes a second cathode active material comprising artificial graphite and a second silicon-based cathode active material, and wherein the content of the first silicon-based cathode active material included in the first cathode active material layer is greater than the content of the second silicon-based cathode active material included in the second cathode active material layer.

Inventors

박주은
김병주
윤대로
박승수

Assignees

주식회사 엘지에너지솔루션

Dates

Publication Date: 20260508
Application Date: 20251029
Priority Date: 20241031

Claims (14)

A negative electrode current collector; a first negative electrode active material layer located on the negative electrode current collector; and a second negative electrode active material layer located on the first negative electrode active material layer; are included. The volume of pores included in the first negative electrode active material layer is 11% to 49% of the total volume of pores included in the entire first negative electrode active material layer and the second negative electrode active material layer, and The first negative electrode active material layer comprises a first negative electrode active material including natural graphite and a first silicon-based negative electrode active material, and The second negative electrode active material layer comprises a second negative electrode active material including artificial graphite and a second silicon-based negative electrode active material, and A cathode in which the content of the first silicon-based cathode active material included in the first cathode active material layer is greater than the content of the second silicon-based cathode active material included in the second cathode active material layer.
In paragraph 1, A cathode in which the ratio ( X1 / X2 ) of the content of the first silicon-based cathode active material (X1) included in the first cathode active material layer and the content of the second silicon-based cathode active material ( X2 ) included in the second cathode active material layer is greater than 1 and less than or equal to 10.
In paragraph 1, The cathode, wherein the first silicon-based negative electrode active material is included in an amount of 5 to 30 weight percent based on the total weight of the first negative electrode active material.
In paragraph 1, The cathode, wherein the second silicon-based negative electrode active material is included in an amount of 1 to 20 weight percent based on the total weight of the second negative electrode active material.
In paragraph 1, The first cathode active material layer has a porosity of 15% to 30%, forming a cathode.
In paragraph 1, The second cathode active material layer is a cathode having a porosity of 20% to 35%.
In paragraph 1, A cathode, wherein the thickness of the first cathode active material layer is 35% to 50% of the total thickness of the first cathode active material layer and the second cathode active material layer.
In paragraph 1, The first silicon-based negative electrode active material and the second silicon-based negative electrode active material each comprise a Si/C composite, forming a negative electrode.
A lithium secondary battery comprising: an electrode assembly including a cathode, an anode, and a separator interposed between the cathode and the anode according to any one of claims 1 to 8; an electrolyte; and a battery case in which the electrode assembly and the electrolyte are housed.
In Paragraph 9, A lithium secondary battery, wherein the ratio of the diameter (R) of the lithium secondary battery to the height (h) of the lithium secondary battery is 0.4 or greater.
In Paragraph 9, The above lithium secondary battery is a lithium secondary battery that is a 46110 cell, a 48110 cell, a 4880 cell, or a 4680 cell.
In Paragraph 9, The above anode and cathode each include an unactive portion in which an active material layer is not formed, and A lithium secondary battery in which at least a portion of the unused portion of the positive electrode and the unused portion of the negative electrode defines an electrode tab.
In Paragraph 12, A lithium secondary battery in which a current collecting plate is coupled to each of the non-positive portion of the positive electrode and the non-negative portion of the negative electrode, and the current collecting plate is connected to an electrode terminal.
In Paragraph 12, The above-mentioned unbought portions of the anode and cathode can be folded independently but are processed into multiple segmented pieces, and A lithium secondary battery in which at least some of the plurality of segments are bent toward the winding center of the electrode assembly.

Description

Negative electrode and lithium secondary battery including the same The present invention relates to a negative electrode and a lithium secondary battery including the same. Recently, lithium-ion batteries have been gaining attention as an energy source for electric vehicles. As the adoption of electric vehicles expands, there is an increasing demand for lithium-ion batteries that offer a longer driving range on a single charge and shorter charging times. A lithium secondary battery is generally manufactured by forming an electrode assembly by interposing a separator between a positive electrode, which contains a positive active material composed of a transition metal oxide containing lithium, and a negative electrode, which contains a negative active material capable of storing lithium ions; inserting the electrode assembly into a battery case; injecting a non-aqueous electrolyte that serves as a medium for transferring lithium ions; and then sealing the case. The non-aqueous electrolyte is generally composed of a lithium salt and an organic solvent capable of dissolving the lithium salt. Conventionally, carbon-based materials such as natural graphite or synthetic graphite have been primarily used as negative active materials for lithium secondary batteries. However, because such carbon-based negative active materials have low capacity and slow reaction rates with lithium, there are limitations in achieving high capacity and rapid charging performance in secondary batteries utilizing them. Therefore, there is a need to develop a cathode capable of achieving high capacity and rapid charging performance when applied to batteries. FIG. 1 is a drawing showing the stacked state of an electrode assembly before winding according to the present invention. FIG. 2 is a cross-sectional view showing the structure of an electrode of an electrode assembly according to one embodiment of the present invention. FIG. 3 is a drawing for explaining the structure of an electrode assembly according to one embodiment of the present invention. FIG. 4 is a cross-sectional view showing the structure of a lithium secondary battery according to one embodiment of the present invention. FIG. 5 is a cross-sectional view showing the structure of a lithium secondary battery according to another embodiment of the present invention. FIG. 6 is a drawing for explaining a battery pack according to the present invention. The present invention will be described in more detail below. Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. The terms used in this specification are used merely to describe exemplary embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, terms such as “comprising,” “having,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof. In the present invention, “pore volume” refers to the volume of pores contained in the electrode active material layer. At this time, pores contained within the electrode active material may not be considered. The pore volume is calculated from the nitrogen adsorption isotherm under a 77K liquid nitrogen atmosphere obtained using BELSORP-MAX (MicrotracBEL corp.) on the cut electrode cross-section after cutting the electrode cross-section, and is calculated using a BJH (Barrett-Joyner-Halenda) plot for pores with a diameter of 2 nm to 185 nm. For example, in the case of a cathode comprising a first cathode active material layer and a second cathode active material layer located on the first cathode active material layer, the volume of the pores of the first cathode active material layer and the volume of the pores of the second cathode active material layer can be measured by the following method. (1) The cathode is cut in cross-section using an ion milling device using an Ar+ ion beam (Manufacturer: Hitachi, Product name: Ar blade5000, Acceleration voltage: 6 kV, Ion beam current: 350 μA). (2) The first cathode active material layer and the second cathode active material layer are distinguished from the first cathode active material layer and the second cathode active material layer by the difference in brightness between the first cathode active material layer and the second cathode active material layer according to the content of silicon-based active material, and the thickness of the first cathode active material layer and